Klicky release for EVA3 and EVA2 on the VCore3


What is a Klicky probe? Why do I need one? How do I get one? Is there a mount available?

Just some of the questions people ask when the words Klicky probe are mentioned on the Discord channels or Facebook groups for the RatRig printers. Well today I’m hopefully going to answer those questions for you, explain why myself and others have spent so much time developing Klicky and it’s derivatives and then show you how to implement it on your VCore3!

So firstly what is a Klicky probe? Klicky is a small dockable probe that uses a microswitch (like what your would fine in a mouse or your printers mechanical end stops) as the means of detecting the surface of your bed. It can be used much like inductive probes or a BLTouch for both homing your Z axis, performing automated 3 point levelling and capturing bed meshes.

Why do you need one? Well lets talk about the other probe options available. Inductive probes are hugely popular due to ease of use and the ability to detect reliably on the most common print surfaces that we use today excluding glass. They are quick and relatively cheap. However they have a few downsides. They only detect metals which means if you swap from textured to smooth PEI sheets or pop a glass bed on top the probe will not detect any change as it will still be sensing the aluminium or spring steel sheet. The other major downside is that although the sensor works at reasonably elevated temperature the reading distance is affected by heat. When printing in an open printer this is normally fine as the probe never really heats up but when working with an enclosed printer the difference between probes at ambient and after a printer has been running for a long time can vary quite significantly. Great so why not use the BLTouch? The BLTouch solves both these issues. It is a touch probe that will physically measures the bed surface and therefore can handle changes in built platform type. It also triggers reliably with temperature change at least until the probe starts to malfunction. It would seem that the electronics are not built to withstand >50c temperatures for extended times and I have personally killed two of them this way and have seen reports of many other people experiencing the same behaviour. Enter Klicky it both physically probes the build surface and is made up of a simple switch, robust against temperature changes and extended time at temperature! And to top it off…you can build one for under £1 which means kitting out all of your printers won’t cost a fortune.

You may of hear of the Unklicky probe? It is a compatible variation of the klicky probe which uses doesn’t use the switch that creates the distinctive click that earnt it the name. It uses a print pin would with some wire as a trigger. I’ll do another post soon about this project!

How good is klicky? Some extensive testing has been done on klicky probes and well they are good and they last a long time. This graph produced by Majarspeed shows 10,000 probe accuracy tests with 5 samples each (so 50,000 probes in total). As you can see the recommended switch performs well and lasts a long time!

Source: https://raw.githubusercontent.com/majarspeed/Unklicky/main/pictures/std deviation.png

Thank you to the developers

The original Klicky was designed by JosAr (find him on discord JosAr#0517). He manages the project on the klicky GitHub repository including community driven modifications please do head over there and take the opportunity to contribute towards his ongoing work!

I originally released VCore3 support for EVA2. Changes for EVA3 and for other MOD compatibility meant that the dock location needed updating for EVA3! Arlock designed the piston based probe extender after testing my initial design. I designed the dock and probe arm. A big thankyou needs to go to Arlock for all the development, testing and pushing me not to be so lazy in the design!

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DISCLAIMER: I use affiliate links in my BOM and in many product links on my site. These links help generate revenue so that I can keep my content both add free and at zero cost to you!

Printed parts

The parts have been released on Printables and will soon be merged into the Klicky GitHub repo

Print everything except the piston probe body and piston with 0.2mm layer height using a 0.4mm nozzle. Recommend 4 walls, 4 top/bottom layers and 40% infill. 

For the piston probe body and piston print them with the same settings but at 0.1mm layer height. You may also want to add a scaled up and down piston (by 1-2%) in addition to the provided size as the fit is important. Suggested orientation is shown below.

For EVA3:

  • 1 x VCore3 Klicky mount
  • 1 x EVA3 klicky probe arm
  • 1 x Klicky probe
  • 1 x Piston Klicky Body
  • 1 x Piston Klicky pin
  • 1 x Klicky dock

For EVA2:

  • 1 x VCore3 Klicky mount
  • 1 x EVA2 klicky probe arm
  • 1 x Klicky probe
  • 1 x Piston Klicky Body
  • 1 x Piston Klicky pin
  • 1 x klicky dock


I have tried my hardest to design this mod to be compatible with as many popular combinations as possible. This work has been extended further by Arlock.


  • Standard frame
  • OpenFront mod
  • Official enclosure


  • All configurations except the tank shroud


  • All configurations

Not compatible with the top MFBS mods. Please see the mod Arlock has released that adds compatibility with that ecosystem.

Setup process

Either watch the video below or scroll further down for a step by step written description of the process.

Assembling the dock

Press a magnet into this hole on the dock. No glue is required as it will be captive inside the assembly (useful for if you need to upgrade in the future!). The orientation doesn’t matter at this stage as we will set the orientation of the one in the probe based on this.

Next bolt the probe dock to the mounting bracket using two M3x18mm bolts. Make sure it is oriented as shown with the magnet on the right hand side and the countersinks on the mounting bracket facing down.

The new dock has been designed to locate accurately off of the existing frame. It fits in the front left corner underneath the idler plate. Carefully remove the two bolts circled in red. You want to avoid knocking the T nuts out of place so when you replace with a long bolt they are in the right spot for it to catch and do back up.

The dock will only fit one way round due to the cutout for the idler bolt. Push the dock firmly into the corner, add the bolts and tighten up.

Assembling Klicky piston probe

Install the read magnet in the Klicky probe body. Add a small drop of superglue and then press the magnet in. This magnet needs to be oriented such that it attracts towards the one in the dock as it will be used to keep the Klicky probe in place. This magnet will sit just under flush to reduce the undocking force.

Remove the spring arm if required and then install the switch by pressing it into the probe body. Make sure the switch aligns with the arrow.

Install the printed piston into the piston housing. Run it back and forth a few times until it is running smoothly. If it is too tight scale the print down a little and try again. We will run 500 probes to bed the probe in but it needs to be reasonably close from the start.

Attach the piston housing to the probe body using two m2 self tapping screws. The piston will compress the switch very slightly when assembled but should not activate it until you press on it. This will also hold the switch in place for the next few steps of adding the remaining magnets.

Install the center magnet on the top face, orientation doesn’t matter unless you already have an existing probe arm installed, in which case match the polarity so it attracts to its corresponding magnet. Again add a small drop of superglue then press the magnet in. I find I can do this by hand but there are helper tools available in on the github. Apply pressure until glue has dried.

IMPORTANT – Wait for the glue to dry. It is really really easy to accidentally pull the magnet back out while you add the next two in.

Install the other 2 magnets using the same method. These should have the opposite polarity to the central one.

Once finished your probe assembly should look like this. Check that the piston when pressed causes the switch to click and then again as you release. Now is the time to use a multimeter and check you get continuity between the two magnets circled above. You should be able to note the continuity being made and broken when you actuate the switch. This ensures the probe is assembled and working.

Assembling the probe arm

Start by feeding two 22AWG wires through the holes at the top. Strip a 10mm length of insulation off of each one. Twist the ends and then feed them back up through the holes at the edges of the magnet cutouts. Once done I like to add a 2pole connector such as a JST SM inline connector so that it can be removed or swapped without messing with your entire print head wiring loom.

Add a small drop of superglue to the central magnet hole. This magnet needs to be oriented such that the central magnet on the probe side will be attracted to it. Use the magnet assembly helpers or a flat surface to insure they sit flat.

IMPORTANT – Wait for the glue to dry. It is really really easy to accidentally pull the magnet back out while you add the next two in.

Install the other 2 magnets using the same method. These should have the opposite polarity to the central one.

Once completed your probe arm should look similar to this. The magnets will be slightly proud of the surface and should be level.

Install the probe arm onto the EVA carriage in the standard probe location and using the standard M3 bolts.


The klicky probe should be wired into the BLTouch port on your controller board. I won’t add wiring diagrams here because there are so many boards being used out there. One wire should be connected to the probe pin and the other to ground. It doesn’t matter which way round as there is no fancy electronics in the switch 🙂.

Configuring RatOS for Klicky

If you installed Klicky before then you will be familiar with the standard set of Klicky macros. These can still be configured to be used with this docking system but many users found this hard to achieve and writing a guide that was able to take into account everyone’s unique setups was difficult! Miklschmidt has been working some magic in the background and there is now a development branch of RatOS that supports stowable probes out of the box. In parallel I’ve provided the configuration for the Klicky probe setup above.

In the near future you will be able to configure your setup for the Klicky probe with just a single line change in the printer.cfg but unfortunately we are not quite there yet. As the branch is still in development there are some changes you need to do to switch over. You can test it out right now though! (And it’s still easier than setting up Klicky the old way!)

WARNING: If you follow the changes below you will be switching to the DEVELOPMENT branch for RatOS. This branch is evolving constantly and has not been tested fully for release. Whilst it was stable at the time of writing this I can’t promise it will always be stable. You will need to swap back once the dev branch gets merged but you shouldn’t have to change your printer config again.

SSH into your printers raspberry pi and swap to the development branch.

ssh pi@ratos.local
cd ~/klipper_config/config
git fetch origin
git checkout development

Update your moonraker.conf to include the two lines relating to the dev branch. (It’s best to include comments so you can easily remember which bits to remove at a later date!)

[update_manager client RatOS]
type: git_repo
path: /home/pi/klipper_config/config
origin: <https://github.com/Rat-OS/RatOS-configuration.git>
install_script: /home/pi/klipper_config/config/scripts/ratos-install.sh
# Dev branch
primary_branch: development

Now is the big step. The development branch requires a newly configured printer.cfg as quite a lot has changed in the background. It’s not hard to do but I advise you take the opportunity to download and save your current one in case something goes wrong and your need to backtrack. Once you have a backup saved navigate to /config/config/templates and open v-core-3-printer.template.cfg. Copy all the text from there. Navigate back to your printer.cfg. Select all the text and delete it. Then paste in the new config.

Configure the new file as per your physical setup. Use the old config as a reference. Make sure to copy over your user overides (unless they relate to the probe usage). Lastly to enable Klicky simply uncomment the lines in the homing section as per the code block below

### Pick your probe and endstops
# BL Touch
#[include config/z-probe/bltouch.cfg]

# Inductive/Capacitive probe
#[include config/z-probe/probe.cfg]

# Euclid probe (please read the RatOS documentation for instructions)
#[include config/z-probe/euclid.cfg]

# Klicky probe (please read the RatOS documentation for instructions)
[include config/z-probe/klicky/klicky.cfg]
#[include config/z-probe/klicky/unklicky.cfg] 

# Physical endstops
[include config/printers/v-core-3/physical-endstops.cfg]

# Sensorless homing (Beware: this requires manual tinkering and does not work if your x/y stepper drivers 
# have clipped DIAG pins). It is strongly encouraged to use physical endstops if you're a beginner. 
# If you still wish to proceed, copy config/templates/sensorless-homing-tmc2209.cfg to the root directory and 
# remove the # from the line below. 
#[include sensorless-homing-tmc2209.cfg]

You should be ready to commission the probe now!

Commissioning the probe

WARNING: Make sure you follow the next few steps before doing anything else. These steps should help check that the dock location and your end stops are all in right place for the probe docking procedure to work smoothly and not cause crashes.

WARNING: make sure you bed is pretty close to level by eye before trying a new probe there is always a risk that if the bed has too greater angle you will crash the nozzle or probe into it.

  1. Home XY axis (DO NOT HOME ALL or Z!)
  2. Move printhead to X13.0 Y6.5
  3. Check that the probe arm sits perfectly over the probe/dock
  4. If it doesn’t adjust your X or Y endstop slightly in the direction needed.
  5. Repeat steps 1-4 until happy
  6. From X13.0 Y6.5 move your printhead about 60mm in positive X. The probe should smoothly come out of the dock.
  7. Move the printhead back to X13 Y6.5. the probe should smoothly move into the dock
  8. Move the printhead by about 60mm in the positive y direction. The probe should slide off the probe arm and stay seated in the dock.
  9. Try running DEPLOY_PROBE and STOW_PROBE. the probe should smoothly dock and undock. If it doesn’t you may need to go back and repeat steps 1-8.
  10. Deploy the probe and move it to the centre of the bed. Run the command below to do 500 probe cycles. This will help bed in the piston section and give you more reliable results going forwards
PROBE_ACCURACY samples=500

If you got through all the steps above without issue then you are good go! Enjoy the Klicky life!

Support 3DP and ME! Help us keep producing tutorials, content and mods!


Reverting back to master RatOS branch

SSH into the pi and run the following commands to swap back to the Master branch

ssh pi@ratos.local
cd ~/klipper_config/config
git fetch origin
git checkout master

Comment out the primary branch line in your moonraker.conf

[update_manager client RatOS]
type: git_repo
path: /home/pi/klipper_config/config
origin: <https://github.com/Rat-OS/RatOS-configuration.git>
install_script: /home/pi/klipper_config/config/scripts/ratos-install.sh
# Dev branch
#primary_branch: development

NOTE: if the reason you are doing this isn’t because the changes on development branch have been merged into master then you will also need to do the next step.

Replace your printer.cfg with the backup you stored at the start of the firmware section.

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